Waveform Window #54: Alpha-Delta Sleep.

Abstract

Alpha-delta sleep is an abnormal rhythm that occurs in slow wave sleep (stage N3) characterized by alpha waves intruding on delta waves and is observed in patients with chronic insomnia, or a chronic pain condition such as fibromyalgia (Van Hoof et al. 2007). Researchers have also linked alpha intrusion to anxiety. An example of this can be a patient exhibiting hypervigilance, which is a sensitivity to the environment including sounds, movements, and changes in surroundings; this hypervigilance can persist in sleep (Van Hoof et al. 2007). When the patient reaches N3 sleep, alpha waves become superimposed on delta waves. Alpha-delta sleep has been studied extensively by polysomnography, but there are few EEG examples with a full array of 10–20 electrodes in the current literature.